How to see what devices are using my modem router ?

Is the Model: A7000|Nighthawk AC1900 WiFi USB Adapter - USB 3.0 listed in your footer involved in this in anyway? Or did you just click the first thing that popped up when you wrote your message?

If not, then it might help to tell people what you do own.

Visit the support pages:

Support | NETGEAR

Feed in your model number and check the documentation for your hardware.

Look for the model number on the label on the device.

Check the manual for something like "View Attached Devices".